CerebrumThe big, folded front part of the brain. A deep cleft divides it into a right and a left cerebral hemisphere.
Longitudinal fissureThe large separation that runs front to back along the midline. It divides the cerebrum into its two hemispheres.
GyrusThe ridge of one of the wrinkles of the cerebrum. The plural is gyri.
SulcusA sulcus is the groove between two gyri. The plural is sulci.
CerebellumIt sits behind the cerebrum and over the brain stem. Its middle strip is the vermis, with a hemisphere on each side.
Spinal cordBehind the cerebellum the medulla oblongata narrows into the spinal cord.
From below 8
Olfactory bulbThe pair of bulbs at the front of the underside. They are the softest parts of the brain and cling to the bone in front of them by many small nerves.
Olfactory tractA band of fibers along the underside of the cerebrum. It carries the bulb's signals back.
Optic nerveEach eye sends one optic nerve to the brain. On a specimen they are short white stumps, cut when the brain was lifted out.
Optic chiasmThe two large white optic nerves meet and form a cross. This is on the underside of the brain. Chiasm means a crossing.
InfundibulumThe little stem the pituitary gland rests on. If the gland was cut away, a hole shows in the end of the stalk.
Mammillary bodiesTwo small rounded bodies close together on the midline. In the sheep they can look like a single bump.
PonsA bulge of fibers running across the brain stem, under the cerebellum. Pons is Latin for bridge.
Medulla oblongataThe club-shaped end of the brain stem. It lies between the pons and the spinal cord.
Cut in half 7
Corpus callosumThe great band of fibers that crosses the midline. It links the right and left hemispheres. The cut goes straight through it.
ThalamusSensory signals, except smell, pass through on the way to the cerebrum. The round mark on the cut face is where the right and left thalami meet.
Pineal bodyA small body on the midline. It is buried under the back of the cerebrum, just in front of the four little hills.
Superior colliculusThe front pair of four bumps on the midbrain, the corpora quadrigemina. It helps turn the eyes toward a sight, sound or touch.
Inferior colliculusThe back pair of the four bumps. It is part of the pathway that carries hearing to the cerebrum.
Fourth ventricleA cavity roofed by the cerebellum. The pons and the medulla are its floor.
Arbor vitaeThe cerebellum's white matter branches like a tree where it is cut. The name is Latin for tree of life.
How this list was compiled: Every name checked on 2026-09-30 in two texts written for the dissection of the sheep brain, both public domain: E. W. Fiske, An Elementary Study of the Brain, Based on the Dissection of the Brain of the Sheep (1913), https://archive.org/details/cu31924024788634, and C. J. Herrick and E. C. Crosby, A Laboratory Outline of Neurology (1918), https://archive.org/details/laboratoryoutlin00herruoft. What each part does, and the names superior colliculus and inferior colliculus, were checked against OpenStax, Anatomy and Physiology 2e, section 13.2 The Central Nervous System, https://openstax.org/books/anatomy-and-physiology-2e/pages/13-2-the-central-nervous-system. That a sheep's olfactory bulbs are much larger for the size of the brain than a human's is from the sheep brain exercise of R. M. Meehan, Laboratory Manual for Fundamentals of Anatomy and Physiology (1999), read through the Internet Archive's full-text search, https://archive.org/details/laboratorymanual0000meeh_v3z8_4rthedi. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work
How it works
This sheep brain diagram labeled in three views follows the order of a dissection: the top, then the underside, then the brain cut in half. The front of the brain is on the left in all three.
Read the full guide
Dorsal view of sheep brain labeled, then the underside
From above you see the cerebrum, split by the longitudinal fissure, its ridges (gyri) and grooves (sulci), the cerebellum behind it and the spinal cord. Turn the brain over. Front to back: olfactory bulbs and tracts, the optic nerves meeting at the optic chiasm, the infundibulum, the mammillary bodies, the pons and the medulla oblongata.
Sheep brain dissection labeled: the midline cut
Cut between the hemispheres. The cut face shows the corpus callosum, the thalamus, the pineal body, the superior and inferior colliculi, the fourth ventricle and the arbor vitae.
No pituitary gland on your specimen? It may have been cut away. Look for the hole it leaves in its stalk, the infundibulum.
The olfactory bulbs are soft and tear off easily. Check that both are still there before you count them as missing.
Questions and answers
What are the parts of a sheep brain?
From above: cerebrum, cerebellum and spinal cord. From below: olfactory bulbs, optic chiasm, infundibulum, mammillary bodies, pons and medulla oblongata. On the cut face: corpus callosum, thalamus, pineal body, colliculi, fourth ventricle and arbor vitae.
How is a sheep brain different from a human brain?
It is smaller, and its olfactory bulbs are much larger for its size, because smell matters more to a sheep. The same main parts are there, which is why classes use it.
What is the arbor vitae in a sheep brain?
The white matter inside the cerebellum. When the cerebellum is cut down the middle, it shows as a white branching pattern like a tree. The name is Latin for tree of life.
Where is the optic chiasm on a sheep brain?
On the underside, on the midline behind the olfactory tracts. The two white optic nerves meet there and form an X.